Recently, hybrid vehicles, having both an engine and a motor as power sources, have been attracting attention in view of fuel efficiency and environmental measure improvements. The hybrid vehicles selectively and appropriately drive one of the engine and the motor or both the engine and the motor in accordance with the driving conditions. Thus, the hybrid vehicles can achieve higher fuel efficiently and lower gas emission than vehicles that are driven only by an engine.
Regarding a power transmission device for a hybrid vehicle, for example, as disclosed in Japanese Unexamined Patent Application Public No. 2007-15679. A device is proposed that can supply oil to predetermined moving components disposed in the vehicle by rotating an oil pump by driving a motor, which acts as a power source. Although such a power transmission device for a hybrid vehicle can supply oil at any time when the vehicle is being driven, it is not possible to appropriately set the rotation speed of the oil pump. This is because the engine and the oil pump rotate together. In order to avoid such a problem, for example, as disclosed in Japanese Unexamined Patent Application Publication No. 2002-542752 and Japanese Unexamined Patent Application Publication No. 2003-191762, devices have been proposed that can appropriately set the rotation speed of the pump when the vehicle is driven by the engine.